[patch] Patch making the TLS initialization avoiding the problematic sysenter

glibc_avoid_sysenter_on_tls_init_with_x86_pic.patch (text/plain), 2.04 KB, created by Francisco Blas Izquierdo Riera on 2014-11-09 19:13:30 UTC

From: Francisco Blas Izquierdo Riera (klondike) <[e-mail]>
Subject: [PATCH] Use the no sysenter syscall when initializing TLS

The glibc 2.20 uses INTERNAL_SYSCALL instead of some custom assembly to
initialize the thread local storage. This is a known chicken and egg problem
which Kevin F. Quinn solved for the sbrk call.

This patch introduces a similar fix in TLS_INIT_TP to fix the issues caused by
commit. Special kudos to blueness for pinpointing commit
9570bc53fcc11d3cfe028989e611266e8d55bd09

This should fix Gentoo bug #528558

This patch is released under the GPLv2 or a higher version license as is the
original file as long as the author and the tester are credited.

Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=528558
Upstream-status: Not supported
Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <[e-mail]>
Reported-by: Toralf Förster <[e-mail]>
Pinpointed-by: Anthony Basile <[e-mail]>
Tested-by: Francisco Blas Izquierdo Riera (klondike) <[e-mail]>

--- sysdeps/i386/nptl/tls.h
+++ sysdeps/i386/nptl/tls.h
@@ -189,6 +189,15 @@
   desc->vals[3] = 0x51;
 }
 
+/* We have no sysenter until the tls is initialized which is a
+   problem on PIC. Thus we need to do the right call depending
+   on the situation.  */
+#ifndef INTERNAL_SYSCALL_NOSYSENTER
+#define TLS_INIT_SYSCALL INTERNAL_SYSCALL
+#else
+#define TLS_INIT_SYSCALL INTERNAL_SYSCALL_NOSYSENTER
+#endif
+
 /* Code to initially initialize the thread pointer.  This might need
    special attention since 'errno' is not yet available and if the
    operation can cause a failure 'errno' must not be touched.  */
@@ -209,7 +218,7 @@
 									      \
      /* Install the TLS.  */						      \
      INTERNAL_SYSCALL_DECL (err);					      \
-     _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
+     _result = TLS_INIT_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 									      \
      if (_result == 0)							      \
        /* We know the index in the GDT, now load the segment register.	      \